The present invention relates to a refrigerating machine oil comprised of a synthetic oil and a refrigerator employing the same.
Conventionally, an HCFC (hydrochloro-fluorocarbon) refrigerant has been mainly employed as a refrigerant of a refrigerator. However, since the HCFC refrigerant destroys the ozone layer in the atmosphere that surrounds the earth, an HFC. (hydrofluorocarbon) refrigerant having a small ozone destruction factor has been considered as a substitute for the HCFC refrigerant. HFC refrigerant hardly dissolves therein mineral oil that has conventionally been employed as a refrigerating machine oil, so that the lubricating performance of a compressor is significantly reduced. Therefore, it is proposed to employ a synthetic oil having a compatibility with the HFC refrigerant as a refrigerating machine oil.
The HFC refrigerant has an intense polarity since it has a combination of a hydrogen atom and a fluorine atom. In contrast to this, contaminations (soiled things) from deteriorated objects of cutting oil, rust preventive oil, hydraulic oil, wash oil, refrigerating machine oil and so on are nonpolar, while a synthetic oil such as an ether oil or the like has both a polar group and a nonpolar group. Therefore, the synthetic oil has a compatibility with the HFC refrigerant having a polarity and an affinity with nonpolar contaminations, therefore dissolving both of them. Then, in a compressor of the above refrigerator, the synthetic oil dissolving therein the contaminations is discharged together with the refrigerant from the compressor and made to circulate through a refrigerant circuit. When the HFC refrigerant is condensed in a condenser, the synthetic oil, which has an intense solubility in a liquid refrigerant, is dissolved in the liquid refrigerant, as a consequence of which the synthetic oil circulates through the refrigerant circuit together with the refrigerant. In this case, the affinity of the HFC refrigerant with the synthetic oil is stronger than the affinity of the contaminations with the synthetic oil, while the nonpolar contaminations are not dissolved in the HFC refrigerant having an intense polarity. Therefore, when the synthetic oil is dissolved into the liquid refrigerant, the contaminations that have been dissolved in the synthetic oil are separated from the synthetic oil and deposited in the liquid refrigerant. Then, the deposited contaminations, which have a high viscosity, adhere to narrow fluid passages of a capillary and an expansion valve, and they are eventually deposited to clog up passages.
The clogging of the capillary and the expansion valve disables the control of the refrigerant flow and causes an abnormal increase in temperature and a backward flow (return) of the fluid to the compressor, significantly impairing the reliability of the refrigerant circuit. Particularly when the ester oil is employed as the refrigerating machine oil, it causes a hydrolysis with water and tends to generate a sludge. In a refrigerator employing a capillary as a decompressor of the refrigerant circuit, the capillary tends to develop more clogging as the capillary tube has a smaller diameter, leading to a problem that it becomes inoperable as a refrigerator.
As a method for preventing the clogging of the capillary and expansion valve, it can be considered to clean the components on a strict standard, thoroughly control the setting and review components of a refrigerating system and the processing steps so that impurities do not enter during a manufacturing process and a setting process. However, these methods require much time as well as an increased number of processes as compared with the conventional cases. Furthermore, they employ an increased amount of detergent in the component cleaning stage and cause much energy consumption, consequently leading to a significant cost increase.
In contrast to this, a refrigerator which can cope with the HFC refrigerant employing only the refrigerating machine oil of the alkylbenzene oil that causes less capillary clogging has been put into practical use. However, the alkylbenzene oil, which is incompatible with the HFC refrigerant, has a property that it hardly dissolves therein the refrigerant gas. Furthermore, it is sometimes the case where a two-layer separation may be caused depending on the temperature range and the ratio of the refrigerant to the refrigerating machine oil. Accordingly, in a separate type air conditioner, an indoor unit and an outdoor unit are connected to each other by way of a long communicating pipe differently from the refrigerator in which all the components are integrated in a unit. Therefore, if the alkylbenzene oil incompatible with the HFC refrigerant is employed as the refrigerating machine oil, then the refrigerating machine oil discharged from the compressor hardly returns to the compressor since the viscosity of the refrigerating machine oil in the refrigerant circuit is high. Therefore, an air conditioner having a long communicating pipe has a problem that an abnormality occurs due to a seizure and abrasion caused by a shortage of refrigerating machine oil in the compressor.
Furthermore, when a large amount of liquid refrigerant lies in the compressor at a low environmental temperature of the compressor or when a large amount of liquid refrigerant returns to the compressor during defrosting, the refrigerating machine oil and the HFC refrigerant separate into two layers inside a dome of the compressor, as a consequence of which a refrigerant rich layer having a greater specific gravity stays in a lower portion of the dome. Then, the refrigerant rich fluid whose viscosity has been significantly reduced is consequently sucked from the inlet port of an oil pump provided in the lowermost portion of the dome of the compressor. A bearing of the compressor is normally designed on the supposition that the viscosity of the refrigerating machine oil is relatively high, according to which the size of the bearing and a frictional motive force at the bearing are considered. Therefore, if the refrigerant rich fluid whose viscosity is significantly reduced is sucked, then a thickness of oil film is reduced to cause a metal contact, and this leads to a problem that the bearing is damaged and the reliability of the compressor is significantly impaired.
Accordingly, it is an object of the present invention to provide a refrigerating machine oil which can easily remove a sludge generated in a refrigerant circuit without reviewing refrigerant system components nor processing steps and is easy to return to a compressor and refrigerator employing the same.
Another object of the present invention is to provide a refrigerating machine oil which can prevent a two-layer separation of oil and refrigerant into two layers inside a compressor and refrigerator employing the same.
In order to achieve the aforementioned objects, the present invention provides a refrigerating machine oil obtained by mixing a first synthetic oil comprised of an alkylbenzene oil with a second synthetic oil other than the alkylbenzene oil.
In regard to the refrigerating machine oil having the above construction, the present applicant has conducted various experiments and studies and discovered that the mixed oil obtained by mixing the first synthetic oil comprised of an alkylbenzene oil and the second synthetic oil (ether oil, ester oil, fluorine oil, carbonate oil or the like) other than the alkylbenzene oil exfoliated sludge generated on inner surfaces of refrigerant system components due to the contaminations (soiled objects) of cutting oil, rust preventive oil, hydraulic oil, wash oil and so on dissolved into a refrigerant. Therefore, according to the above refrigerating machine oil, the sludge adhered to the inner surfaces of a capillary and an expansion valve is exfoliated and removed by the alkylbenzene oil. Therefore, the sludge can be removed to prevent the capillary and the expansion valve from being clogged without reviewing the refrigerant system components nor their processing steps. By employing a synthetic oil that is easy to dissolve into an HFC refrigerant in, for example, a refrigerator employing the HFC refrigerant, the synthetic oil discharged together with the refrigerant from a compressor circulates through a refrigerant circuit and returns to the compressor. Accordingly, there is no such problem that the synthetic oil is hard to return and causes a poor lubrication, so that the lubricating performance of the compressor can be maintained.
According to the refrigerating machine oil of one embodiment, the second synthetic oil is provided by an ether oil.
With this arrangement, for example, when an HFC refrigerant is employed, the ether oil is well dissolved in the HFC refrigerant and circulates through the refrigerant circuit. Accordingly, there is no such problem that the ether oil discharged together with the refrigerant from the compressor is hard to return, so that the sludge adhered to the inner surfaces of small-diameter portions of the capillary and the expansion valve can be exfoliated and removed by the alkylbenzene oil while maintaining the lubricating performance of the compressor. The alkylbenzene oil incompatible with the HFC refrigerant is well dissolved in the ether oil, and therefore, the alkylbenzene oil is transferred to the inside of the refrigerant circuit even in a state in which the alkylbenzene oil is dissolved in the ether oil, so that the sludge can effectively be removed.
According to the refrigerating machine oil of one embodiment, the second synthetic oil is provided by an ester oil.
With this arrangement, for example, when an HFC refrigerant is employed, the ester oil is well dissolved in the HFC refrigerant and circulates through the refrigerant circuit. Accordingly, there is no such problem that the ester oil discharged together with the refrigerant from the compressor is hard to return, so that the sludge adhered to the inner surfaces of small-diameter portions of the capillary or the expansion valve can be exfoliated and removed by the alkylbenzene oil while maintaining the lubricating performance of the compressor. The alkylbenzene oil incompatible with the HFC refrigerant is well dissolved in the ester oil, and therefore, the alkylbenzene oil is transferred to the inside of the refrigerant circuit even in a state in which the alkylbenzene oil is dissolved in the ester oil, so that the sludge can effectively be removed.
According to the refrigerating machine oil of one embodiment, the second synthetic oil is comprised of an ether oil and an ester oil.
With this arrangement, for example, when an HFC refrigerant is employed, the ether oil and the ester oil are well dissolved in the HFC refrigerant and circulate through the refrigerant circuit. Accordingly, there is no such problem that the ether oil and the ester oil discharged together with the refrigerant from the compressor are hard to return, so that the sludge adhered to the inner surfaces of small-diameter portions of the capillary and the expansion valve can be exfoliated and removed by the alkylbenzene oil while maintaining the lubricating performance of the compressor. The alkylbenzene oil incompatible with the HFC refrigerant is well dissolved in the ether oil and the ester oil, and therefore, the alkylbenzene oil is transferred to the inside of the refrigerant circuit even in a state in which the alkylbenzene oil is dissolved in the ether oil and the ester oil, so that the sludge can effectively be removed. The ester oil is hydrolyzed by water but deterioration by oxidation scarcely occurs. On the contrary, the ether oil is deteriorated by oxidation but scarcely hydrolyzed by water since it withstands water. Therefore, by setting the ratio of the ether oil to the ester oil to 1:1, there can be obtained a refrigerating machine oil of which the degree of deterioration by oxidation and the degree of hydrolysis by water are each reduced half.
According to the refrigerating machine oil of one embodiment, the second synthetic oil is a fluorine oil.
With this arrangement, for example, when an HFC refrigerant is employed, the fluorine oil is well dissolved in the HFC refrigerant and circulates through the refrigerant circuit. Accordingly, there is no such problem that the fluorine oil discharged together with the refrigerant from the compressor is hard to return, so that the sludge adhered to the inner surfaces of small-diameter portions of the capillary and the expansion valve can be exfoliated and removed by the alkylbenzene oil while maintaining the lubricating performance of the compressor.
According to the refrigerating machine oil of one embodiment, the second synthetic oil is a carbonate oil.
With this arrangement, for example, when an HFC refrigerant is employed, the carbonate oil is well dissolved in the HFC refrigerant and circulates through the refrigerant circuit. Accordingly, there is no such problem that the carbonate oil discharged together with the refrigerant from the compressor is hard to return, so that, while maintaining the lubricating performance of the compressor, the sludge adhered to the inner surfaces of small-diameter portions of the capillary and the expansion valve can be exfoliated and removed by the alkylbenzene oil.
According to the refrigerating machine oil of one embodiment, the ratio of the alkylbenzene oil relative to the refrigerating machine oil is set to 1 to 50 percent by weight.
With this arrangement, the ratio of the alkylbenzene oil is preferably smaller for the synthetic oil discharged together with the refrigerant from the compressor to circulate through the refrigerant circuit and return to the compressor, whereas the ratio of the alkylbenzene oil is preferably greater for the removal of the sludge. Therefore, by making the ratio of the alkylbenzene oil as great as possible while maintaining the oil return of the synthetic oil according to the refrigerant circuit, effective sludge removal is executed. When the ratio of the alkylbenzene oil relative to the refrigerating machine oil exceeds 50 percent by weight, the ratio of the alkylbenzene oil is consequently increased too much with respect to, for example, the HFC refrigerant in which the alkylbenzene oil does not dissolve, for which the refrigerating machine oil discharged together with the refrigerant from the compressor is hard to circulate the refrigerant circuit and return. When the ratio of the alkylbenzene oil relative to the refrigerating machine oil is not greater than 50 percent by weight, the synthetic oil discharged together with the refrigerant from the compressor circulates through the refrigerant circuit and surely returns. The removal of the sludge is insufficient when the ratio of the alkylbenzene oil relative to the refrigerating machine oil is smaller than 1 percent by weight, whereas the sludge removal effect is produced when the ratio is not smaller than 1 percent by weight.
According to the refrigerating machine oil of one embodiment, the ratio of the alkylbenzene oil relative to the refrigerating machine oil is made not smaller than five percent by weight and the viscosity of the refrigerating machine oil is made not smaller than 2.5 cst at a temperature of 100xc2x0 C.
According to the experiments and study conducted by the present applicant, it was discovered that the sludge generated on the inner surface of the capillary due to the contaminations of cutting oil, rust preventive oil, hydraulic oil, wash oil and so on dissolved into the refrigerant (HFC refrigerant according to the experiment) was exfoliated and surely removed when the ratio of the alkylbenzene oil relative to the refrigerating machine oil is not smaller than five percent by weight, so that the clogging of the capillary was eliminated. It was also discovered that the sludge generated on the inner surface of the capillary was not able to be removed when the ratio of the alkylbenzene oil relative to the refrigerating machine oil was smaller than five percent by weight. It was further discovered through an experiment that the ratio of metal contact becomes almost zero percent by making the viscosity of the refrigerating machine oil not smaller than 2.5 cst, so that the oil films of the bearing and so on were maintained. It was further discovered that the ratio of metal contact increases and the oil films of the bearing and so on were not sufficiently secured when the viscosity of the refrigerating machine oil was made smaller than 2.5 cst. Therefore, by making the ratio of the alkylbenzene oil relative to the refrigerating machine oil not smaller than five percent by weight and making the viscosity of the refrigerating machine oil not smaller than 2.5 cst, the clogging of the capillary and the expansion valve by the sludge can be prevented and the oil films of the bearing and so on are maintained normal throughout the entire region of the operating range, so that the reliability of the compressor can be maintained.
According to the refrigerating machine oil of one embodiment, the oil concentration of the refrigerant rich layer is made not smaller than 2.5 percent by weight when the refrigerating machine oil and the HFC refrigerant are separated into two layers at a temperature of 0xc2x0 C.
With this arrangement, it was discovered through an endurance test that, when the HFC refrigerant and the refrigerating machine oil were separated into two layers inside the compressor, the oil films of the bearing and so on of the compressor were maintained appropriate and no problem has occurred when the oil concentration of the refrigerant rich layer of the layers that had separated into two layers was not smaller than 2.5 percent by weight. It was also discovered that the oil films of the bearing and so on of the compressor were reduced and the bearing and so on were damaged when the oil concentration of the refrigerant rich layer of the layers that had separated into two layers was smaller than 2.5 percent by weight. Therefore, even when the HFC refrigerant lies in the compressor in an operation stop state and the HFC refrigerant and the refrigerating machine oil are separated into two layers, the two-layer separation temperature of the HFC refrigerant and the base oil and the ratio of the alkylbenzene oil relative to the refrigerating machine oil are adjusted so that the oil concentration of the refrigerant rich layer becomes not smaller than 2.5 percent by weight. Therefore, the oil films are maintained and the bearing and so on are not damaged, so that the reliability of the compressor can be maintained. When the second synthetic oil is the ether oil, the ether oil can easily adjust the two-layer separation temperature of the HFC refrigerant and the ether oil, so that the two-layer separation temperature of the refrigerant and the mixed oil (alkylbenzene oil and ether oil) can be reduced even when an increased amount of alkylbenzene oil is incorporated therein as compared with the ester oil.
According to the refrigerating machine oil of one embodiment, the ratio of the alkylbenzene oil relative to the refrigerating machine oil is made not smaller than five percent by weight and the two-layer separation temperature of the HFC refrigerant and the refrigerating machine oil is made not higher than 10xc2x0 C.
With this arrangement, when the ratio of the alkylbenzene oil relative to the refrigerating machine oil is not smaller than five percent by weight, the sludge generated on the inner surfaces of the capillary and the expansion valve due to the contaminations of cutting oil, rust preventive oil, hydraulic oil, wash oil and so on dissolved into the HFC refrigerant is exfoliated and surely removed, so that the clogging of the capillary is eliminated. According to the results of an endurance test conducted by the present applicant, it was discovered that the refrigerating machine oil and the liquid refrigerant were uniformly dissolved in an operating state at a temperature of not lower than 10xc2x0 C. by making the two-layer separation temperature of the HFC refrigerant and the refrigerating machine oil not higher than 10xc2x0 C. even when the liquid refrigerant returned into the dome of the compressor. It was also discovered that the refrigerating machine oil and the liquid refrigerant were sometimes not uniformly dissolved when the two-layer separation temperature of the HFC refrigerant and the refrigerating machine oil exceeded the temperature of 10xc2x0 C. Therefore, by making the ratio of the alkylbenzene oil relative to the refrigerating machine oil not smaller than five percent by weight and making the two-layer separation temperature of the HFC refrigerant and the refrigerating machine oil not higher than 10xc2x0 C., a mixture of the refrigerant and the mixed oil having an appropriate viscosity is sucked into an oil pump, so that the reliability of the compressor can be maintained. When the second synthetic oil is the ether oil, the ether oil can easily adjust the two-layer separation temperature of the HFC refrigerant and the ether oil, so that the two-layer separation temperature of the refrigerant and the mixed oil (alkylbenzene oil and ether oil) can be reduced even when an increased amount of alkylbenzene oil is incorporated.
The present invention also provides a refrigerator employing one of the aforementioned refrigerating machine oils.
According to the refrigerator constructed as above, the sludge adhered to the inner surfaces of the small-diameter portions of the capillary and the expansion valve is exfoliated and removed by the alkylbenzene oil, and therefore, the capillary and the expansion valve can be prevented from being clogged. Furthermore, the above arrangement can obviates the need for a refrigerant system component cleaning process for removing the cutting oil, rust preventive oil and the hydraulic oil that cause the sludge, so that the number of processes and cost can be reduced.
According to the refrigerator of one embodiment, an HFC (hydrofluorocarbon) refrigerant is employed.
With this arrangement, the sludge adhered to the inner surfaces of the small-diameter portions of the capillary and the expansion valve can be exfoliated and removed by the alkylbenzene oil although the sludge is easily generated on, in particular, the inner surfaces of the small-diameter portions of the capillary and the expansion valve when a synthetic oil having a compatibility with the HFC refrigerant is employed as a refrigerating machine oil.
According to the refrigerator of one embodiment, a capillary is employed as a decompressor.
With this arrangement, the sludge adhered to the inner surface of the small-diameter portion of the capillary is exfoliated and removed by the alkylbenzene oil. Therefore, an inexpensive capillary can be employed, so that the cost of the refrigerator can be reduced.
According to the refrigerator of one embodiment, an HFC refrigerant and a high-pressure dome type compressor are employed and the ratio of the alkylbenzene oil relative to the refrigerating machine oil is made not smaller than five percent by weight and the viscosity of the refrigerating machine oil is made not smaller than 2.5 cst at a temperature of 100xc2x0 C.
According to the results of the aforementioned test and study, by making the ratio of the alkylbenzene oil relative to the refrigerating machine oil not smaller than five percent by weight and making the viscosity of the refrigerating machine oil not smaller than 2.5 cst at a temperature of 100xc2x0 C., the clogging of the capillary and the expansion. valve due to the sludge can be prevented and the oil films of the bearing and so on are maintained normal throughout the entire region of the operating range, so that the reliability of the high-pressure dome type compressor having a high oil temperature can be maintained. It is to be noted that the high-pressure dome type compressor has a construction in which the refrigerant flows to a discharge pipe via an inlet pipe, a compressing portion and the container (high-pressure dome) of the compressor and the refrigerating machine oil is reserved in a high-temperature high-pressure portion inside the high-pressure dome.
According to the refrigerator of one embodiment, the oil concentration of the refrigerant rich layer when the refrigerating machine oil and the HFC refrigerant are separated into two layers at a temperature of 0xc2x0 C. is made not smaller than 2.5 percent by weight.
With this arrangement, in the case where the HFC refrigerant and the refrigerating machine oil are separated into two layers inside the compressor, the oil films of the bearing and so on of the compressor are maintained appropriate when the oil concentration of the refrigerant rich layer of the layers that have separated into two layers is not smaller than 2.5 percent by weight, causing no problem in terms of the reliability. Therefore, in the case of the high-pressure dome type compressor in which the two-layer separation of the HFC refrigerant and the refrigerating machine oil is a problem, the two-layer separation temperature of the HFC refrigerant and the base oil and the ratio of the alkylbenzene oil relative to the refrigerating machine oil are adjusted so that the oil concentration of the refrigerant rich layer becomes not smaller than 2.5 percent by weight even when the HFC refrigerant lies in the compressor in the operation stop state and the HFC refrigerant and the refrigerating machine oil are separated into two layers. Therefore, the oil films are maintained to cause no damage of the bearing and so on, so that the reliability of the compressor can be maintained. When the second synthetic oil is the ether oil, the ether oil can easily adjust the two-layer separation temperature of the HFC refrigerant and the ether oil, so that the two-layer separation temperature of the refrigerant and the mixed oil (alkylbenzene oil and ether oil) can be reduced even when an increased amount of alkylbenzene oil is incorporated therein as compared with the ester oil.
According to the refrigerator of one embodiment, an HFC refrigerant and a low-pressure dome type compressor are employed, the ratio of the alkylbenzene oil relative to the refrigerating machine oil is made not smaller than five percent by weight and the two-layer separation temperature of the HFC refrigerant and the refrigerating machine oil is made not higher than 10xc2x0 C.
With this arrangement, according to the results of the aforementioned test and study, when the ratio of the alkylbenzene oil relative to the refrigerating machine oil is not smaller than five percent by weight, the sludge generated on the inner surface of the capillary due to the contaminations of cutting oil, rust preventive oil, hydraulic oil, wash oil and so on dissolved into the HFC refrigerant is exfoliated and surely removed, so that the clogging of the capillary and the expansion valve is eliminated. In the case of the low-pressure dome type compressor in which the two-layer separation of the HFC refrigerant and the refrigerating machine oil tends to occur, the ratio of the alkylbenzene oil must be reduced as compared with the high-pressure dome type. By making the two-layer separation temperature of the HFC refrigerant and the refrigerating machine oil not higher than 10xc2x0 C., the refrigerating machine oil and the liquid refrigerant are uniformly dissolved in an operating state at a temperature of not lower than 10xc2x0 C. by making the two-layer separation temperature of the HFC refrigerant and the refrigerating machine oil not higher than 10xc2x0 C. even when the liquid refrigerant returned into the dome of the compressor. Therefore, by making the ratio of the alkylbenzene oil relative to the refrigerating machine oil not smaller than five percent by weight and making the two-layer separation temperature of the HFC refrigerant and the refrigerating machine oil not higher than 10xc2x0 C., a mixture of the refrigerant and the mixed oil having an appropriate viscosity is sucked into the oil pump, so that the reliability of the low-pressure dome type compressor can be maintained. It is to be noted that the low-pressure dome type compressor has a construction in which the refrigerant flows to a discharge pipe via an inlet pipe, the container (low-pressure dome) of the compressor and a compressing portion and the refrigerating machine oil is reserved in a low-temperature low-pressure portion inside the low-pressure dome. When the second synthetic oil is the ether oil, the ether oil can easily adjust the two-layer separation temperature of the HFC refrigerant and the ether oil, so that the two-layer separation temperature of the refrigerant and the mixed oil (alkylbenzene oil and ether oil) can be reduced even when an increased amount of alkylbenzene oil is incorporated therein as compared with the ester oil.
According to the refrigerator of one embodiment, an HCFC refrigerant is employed.
With this arrangement, the sludge adhered to the inner surfaces of the small-diameter portions of the capillary and the expansion valve can be exfoliated and removed by the alkylbenzene oil although the sludge is easily generated on, in particular, the inner surfaces of the small-diameter portions of the capillary and the expansion valve when a synthetic oil is employed as a refrigerating machine oil.
According to the refrigerator of one embodiment, an HCFC refrigerant is employed and a capillary is employed for its decompressor.
With this arrangement, the refrigerating machine oil also has a compatibility with the HCFC refrigerant, and the sludge adhered to the inner surface of the small-diameter portion of the capillary can be exfoliated and removed by the alkylbenzene oil mixed in the refrigerating machine oil. Since the sludge adhered to the inner surface of the small-diameter portion of the capillary is exfoliated and removed by the alkylbenzene oil, an inexpensive capillary can be employed, so that the cost of the refrigerator can be reduced. The refrigerator filled with the above refrigerating machine oil can easily replace the HCFC refrigerant with the alternative refrigerant of the HFC refrigerant (so-called the retrofit can easily be achieved) without changing the refrigerating machine oil.
According to the refrigerator of one embodiment, an HCFC refrigerant and a high-pressure dome type compressor are employed, the ratio of the alkylbenzene oil relative to the refrigerating machine oil is made not smaller than five percent by weight and the viscosity of the refrigerating machine oil is made not smaller than 2.5 cst at a temperature of 100xc2x0 C.
With this arrangement, according to the results of the aforementioned test and study, by making the ratio of the alkylbenzene oil relative to the refrigerating machine oil not smaller than five percent by weight and making the viscosity of the refrigerating machine oil not smaller than 2.5 cst at a temperature of 100xc2x0 C., the clogging of the capillary and the expansion valve by the sludge can surely be prevented and the oil films of the bearing and so on are maintained normal throughout the entire region of the operating range, so that the reliability of the high-pressure dome type compressor having a high oil temperature can be maintained. The refrigerator filled with the above refrigerating machine oil can easily replace the HCFC refrigerant with the alternative refrigerant of the HFC refrigerant without changing the refrigerating machine oil.
According to the refrigerator of one embodiment, the oil concentration of the refrigerant rich layer is made not smaller than 2.5 percent by weight when the refrigerating machine oil and the HCFC refrigerant are separated into two layers at a temperature of 0xc2x0 C.
With this arrangement, in the case where the HFC refrigerant and the refrigerating machine oil are separated into two layers inside the compressor, the oil films of the bearing and so on of the compressor are maintained appropriate when the oil concentration of the refrigerant rich layer of the layers that have separated into two layers is not smaller than 2.5 percent by weight, causing no problem in terms of the reliability. Therefore, in the case of the high-pressure dome type compressor in which the two-layer separation of the HCFC refrigerant and the refrigerating machine oil is a problem, the two-layer separation temperature of the HCFC refrigerant and the base oil and the ratio of the alkylbenzene oil relative to the refrigerating machine oil are adjusted so that the oil concentration of the refrigerant rich layer becomes not smaller than 2.5 percent by weight even when the HCFC refrigerant lies in the compressor in the operation stop state and the HCFC refrigerant and the refrigerating machine oil are separated into two layers. Therefore, the oil films are maintained to cause no damage of the bearing and so on, so that the reliability of the compressor can be maintained. The refrigerator filled with the above refrigerating machine oil can easily replace the HCFC refrigerant with the alternative refrigerant of the HFC refrigerant without changing the refrigerating machine oil. When the second synthetic oil is the ether oil, the ether oil can easily adjust the two-layer separation temperature of the HFC refrigerant and the ether oil, so that the two-layer separation temperature of the refrigerant and the mixed oil (alkylbenzene oil and ether oil) can be reduced even when an increased amount of alkylbenzene oil is incorporated as compared with the ester oil.
According to the refrigerator of one embodiment, an HCFC refrigerant and a low-pressure dome type compressor are employed, the ratio of the alkylbenzene oil relative to the refrigerating machine oil is made not smaller than five percent by weight and the two-layer separation temperature of the refrigerating machine oil and the HCFC refrigerant is made not higher than 10xc2x0 C.
With this arrangement, according to the results of the aforementioned test and study, when the ratio of the alkylbenzene oil relative to the refrigerating machine oil is not smaller than five percent by weight, the sludge generated on the inner surface of the capillary due to the contaminations of cutting oil, rust preventive oil, hydraulic oil, wash oil and so on dissolved into the HCFC refrigerant is exfoliated and surely removed, so that the clogging of the capillary is eliminated. In the case of the low-pressure dome type compressor in which the two-layer separation of the HCFC refrigerant and the refrigerating machine oil tends to occur, by making the two-layer separation temperature not higher than 10xc2x0 C., the refrigerating machine oil and the liquid refrigerant are uniformly dissolved in an operating state at a temperature not lower than 10xc2x0 C. even when the liquid refrigerant returns to the inside of the dome of the compressor. Therefore, a mixture of the refrigerant and the refrigerating machine oil having an appropriate viscosity is sucked into the oil pump, so that the reliability of the low-pressure dome type compressor can be maintained. The refrigerator filled with the above refrigerating machine oil can easily replace the HCFC refrigerant with the alternative refrigerant of the HFC refrigerant without changing the refrigerating machine oil. When the second synthetic oil is the ether oil, the ether oil can easily adjust the two-layer separation temperature of the HFC refrigerant and the ether oil, so that the two-layer separation temperature of the refrigerant and the mixed oil (alkylbenzene oil and ether oil) can be reduced even when an increased amount of alkylbenzene oil is incorporated as compared with the ester oil.
According to the refrigerator of one embodiment, there are employed a swing type compressor comprising: a roller which is rotatably fitted on an eccentric section of a driving shaft; a blade which is integrally fixed to an outer peripheral surface of the roller and extends outwardly of a radius of the roller, thereby separating a cylinder chamber inside a cylinder into a compression chamber and an inhalation chamber; and a support member which is rotatably supported in the cylinder and in which is formed a reception groove that receives and guides a protruding side tip portion of the blade.
According to the refrigerator constructed as above, in the swing type compressor, the blade is fixed to the roller and the tip portion of the blade is guided by the reception groove of the rotatable support member. Therefore, the surface of the blade comes in surface contact with the support member to achieve sealing, generating no boundary lubrication state. Therefore, even when the alternative fleon refrigerant is employed taking the environmental safety into consideration, the sludge adhered to the inner surfaces of the small-diameter portions of the capillary and the expansion valve can be exfoliated and removed by the alkylbenzene oil. Furthermore, the blade of the compressor is made to slide in surface contact with the support member, and therefore, the deterioration of the lubricating oil can be prevented, so that the seizure can be prevented.